Polarization reuse and beam-forming techniques for aeronautical broadband systems

ABSTRACT

Aeronautical broadband communication is enhanced by providing an apparatus having a first antenna configured to communicate using a signal orientation corresponding to a first polarization, and a second antenna configured to communicate using a signal orientation corresponding to a second polarization, where the second polarization has at least one characteristic difference from the first polarization. Additional antennas may be used, where multiple antennas share one polarization, and multiple other antennas share a different polarization, and signals from like-polarized antennas are combined for beam-formation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application which claims the benefit ofU.S. application Ser. No. 11/739,887 filed Apr. 25, 2007, and U.S.Provisional Application No. 60/795,037 filed Apr. 25, 2006, and of U.S.Provisional Application No. 60/851,297, filed Oct. 13, 2006. Theaforementioned provisional applications' disclosures are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to aeronautical broadbandsystems, and more particularly to methods and apparatuses forpolarization reuse and beam-forming for aeronautical broadband systems.

2. Background

Wireless communication systems are widely deployed to provide varioustypes of communication such as voice and data. A typical wireless datasystem, or network, provides multiple users access to one or more sharedresources. A system may use a variety of multiple access techniques suchas frequency division multiplexing (FDM), time division multiplexing(TDM), code division multiplexing (CDM), and others. Examples ofwireless networks include cellular-based data systems. The following areseveral such examples: (1) the “TIA/EIA-95-B Mobile Station-Base StationCompatibility Standard for Dual-Mode Wideband Spread Spectrum CellularSystem” (the IS-95 standard), (2) the standard offered by a consortiumnamed “3rd Generation Partnership Project” (3GPP) and embodied in a setof documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offeredby a consortium named “3rd Generation Partnership Project 2” (3GPP2) andembodied in “TR-45.5 Physical Layer Standard for cdma2000 SpreadSpectrum Systems” (the IS-2000 standard), and (4) the high data rate(HDR) system that conforms to the TIA/EIA/IS-856 standard (the IS-856standard).

In general, signal strength is a critical factor in establishing acommunication link with good quality of service (QoS). In the case ofbroadband communications with multiple subscribers, the signal strengthprovided to subscribers' wireless communication devices (WCDs) by thebase station and by the WCDs to the base station is limited. In thefurther case of aeronautical broadband systems, aeronautical wirelesscommunication devices there is a continuous clear line-of-sight betweenthe wireless communication device and the base station.

New methods and apparatuses are needed to improve coverage areautilization above the ground, and to take advantage of the clearline-of-sight available in aeronautical systems. It would beadvantageous to provide cost-effective methods and apparatus forpolarization reuse and beam-forming for aeronautical broadband systems.

SUMMARY

According to the present inventive subject matter, aeronauticalbroadband communication is enhanced by providing an apparatus having afirst antenna configured to communicate using a signal orientationcorresponding to a first polarization, and a second antenna configuredto communicate using a signal orientation corresponding to a secondpolarization, where the second polarization has at least onecharacteristic difference from the first polarization.

The first polarization may be substantially orthogonal to the secondpolarization. A first radiator may be configured to communicate using asignal orientation corresponding to the first polarization, and a secondradiator configured to communicate using a signal orientationcorresponding to the second polarization. The radiators may be in onecell site or in adjacent respective cell sites. A processor may receivesignals from each of the antennas, calculate a signal qualitymeasurement from each of the antennas; and handoff communicationresponsibilities from one of the antennas to the other of the antennaswhen the signal quality measurement of one of the antennas is lower thanthe signal quality measurement of the other of the antennas. The signalquality measurement may be a signal to interference and noise ratio(SINR), a signal to interference ratio (SIR), or a signal to noise ratio(SNR).

The apparatus may include a third antenna configured to communicateusing a signal orientation corresponding to the first polarization, anda fourth antenna configured to communicate using a signal orientationcorresponding to the second polarization. A processor is configured tocombine the signals received from the first antenna and the thirdantenna in a proportion based on an algorithm for selecting a signalaccording to a first signal quality measurement. A processor, which canbe either the same processor or a different processor, is configured tocombine the signals received from the second antenna and the fourthantenna in a proportion based on an algorithm for selecting a signalaccording to a second signal quality measurement. At least one of thesignal quality measurements may include a Signal to Interference plusNoise Ratio (SINR), a Signal to Interference Ratio (SIR), or a Signal toNoise Ratio (SNR). The algorithm may include one of a Minimum MeanSquared Error (MMSE) algorithm, an Equal Gain Combining (EGC) algorithm,a Maximal Ratio Combining (MRC) algorithm applied to the first andsecond signal quality measurements.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication by providing an apparatus having asingle antenna capable of, in a first configuration, communicating usinga signal orientation corresponding to a first polarization, and in asecond configuration, communicating using a signal orientationcorresponding to a second polarization substantially orthogonal to thefirst polarization.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication by establishing a firstcommunication link with a first radiator using a signal orientationcorresponding to a first polarization, and establishing a secondcommunication link with a second radiator using a signal orientationcorresponding to a second polarization having at least onecharacteristic difference from the first polarization.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a system having means forestablishing a communication link with a first radiator using a signalorientation corresponding to a first polarization, and means forestablishing a communication link with a second radiator using a signalorientation corresponding to a second polarization substantiallyorthogonal to the first polarization.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a machine readable mediumhaving instructions for establishing a communication link with a firstradiator using a signal orientation corresponding to a firstpolarization and instructions for establishing a communication link witha second radiator using a signal orientation corresponding to a secondpolarization substantially orthogonal to the first polarization.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a processor having circuitryfor establishing a communication link with a first radiator using asignal orientation corresponding to a first polarization, and circuitryfor establishing a communication link with a second radiator using asignal orientation corresponding to a second polarization substantiallyorthogonal to the first polarization.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with an apparatus having a firstantenna, a second antenna, and a processor configured to combine thesignals received from the first antenna and the second antenna in aproportion based on an algorithm for selecting a signal according to asignal quality measurement. The signal quality measurement may include aSignal to Interference plus Noise Ratio (SINR), Signal to InterferenceRatio (SIR), or Signal to Noise Ratio (SNR). The apparatus may alsoinclude a third antenna, a fourth antenna, and a processor configured tocombine the signals received from the third antenna and the fourthantenna in a proportion based on an algorithm for selecting a signalaccording to a signal quality measurement, where the first antenna andthe second antenna are configured to communicate using a signalorientation corresponding to a first polarization, and the third antennaand the fourth antenna are configured to communicate using a signalorientation corresponding to a second polarization orthogonal to thefirst polarization.

The signal quality measurement may include a first measurement from thefirst antenna and a second measurement from the second antenna, wherethe algorithm includes one of a Minimum Mean Squared Error (MMSE)algorithm, an Equal Gain Combining (EGC) algorithm, a Maximal RatioCombining (MRC) algorithm applied to the first measurement and thesecond measurement. The algorithm may select a radiator forcommunication characteristics, and the processor may combine the signalsreceived from the first antenna and the second antenna so as to form abeam toward the radiator.

The apparatus may have a first transmit chain which produces signals ata ratio determined from the algorithm, and a second transmit chain whichproduces signals at a ratio determined from the algorithm. The firsttransmit chain may have at least one filter and at least one poweramplifier, and the second transmit chain may have at least one filterand at least one power amplifier. The algorithm may select a radiatorfor communication characteristics, the processor may combine the signalsreceived from the first antenna and the second antenna so as to form abeam toward the radiator, and the processor may further produce signalsat the first transmit chain and the second transmit chain so as to forma beam toward the radiator.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a method having the steps of:performing a signal quality measurement based on signals from a firstantenna, performing a second signal quality measurement based on signalsfrom a second antenna, feeding the first signal quality measurement andthe second signal quality measurement into an algorithm, and combiningthe signals received from the first antenna and the second antenna at aratio determined from the algorithm.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a system having a first meansfor receiving signals and means for performing a first signal qualitymeasurement based on signals from the first receiving means, a secondmeans for receiving signals and means for performing a second signalquality measurement based on signals from the second receiving means,means for determining a desirable proportion for combining the signalsreceived from the first receiving means and the second receiving meansbased on the first signal quality measurement and the second signalquality measurement, and means for combining the signals received fromthe first receiving means and the second receiving means in theproportion.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a machine readable mediumhaving instructions for performing a first signal quality measurementbased on signals from a first antenna, instructions for performing asecond signal quality measurement based on signals from a secondantenna, instructions for feeding the first signal quality measurementand the second signal quality measurement into an algorithm, andinstructions for combining signals received from the first antenna andthe second antenna at a ratio determined from the algorithm.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a processor having circuitryfor performing a first signal quality measurement based on signals froma first antenna, circuitry for performing a second signal qualitymeasurement based on signals from a second antenna, circuitry forfeeding the first signal quality measurement and the second signalquality measurement into a combining algorithm, and circuitry forcombining the signals received from the first antenna and the secondantenna at a ratio determined from the algorithm.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, nature, and advantages of the present invention willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify corresponding items throughout and wherein:

FIG. 1 a is a diagram illustrating an example of an aeronauticalbroadband communication apparatus.

FIG. 1 b is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

FIG. 2 is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

FIG. 3 is a flow diagram showing the functional operation of anaeronautical broadband communication in accordance with the invention.

FIG. 4 is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

FIG. 5 is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

FIG. 6 is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

FIG. 7 is a flow diagram showing the functional operation of anaeronautical broadband communication in accordance with the invention.

FIG. 8 is a diagram illustrating another example of an aeronauticalbroadband communication apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. The word “example” is used hereinto mean “a non-limiting example.” Each example provided herein is anillustration of merely one embodiment; many others may exist, and noprovided example should be construed as limiting an otherwise broadercategory.

Overview

Aeronautical broadband communication is enhanced by providing a firstantenna configured to communicate using a signal orientationcorresponding to a first polarization, and a second antenna configuredto communicate using a signal orientation corresponding to a secondpolarization having at least one characteristic difference from thefirst polarization. The first polarization may be substantiallyorthogonal to the second polarization. Radiators of orthogonalpolarization may be placed in the same or adjacent cell sites. Aprocessor may handoff communication responsibilities from one of theantennas to the other of the antennas. Aeronautical broadbandcommunication is also enhanced by providing a first antenna, a secondantenna, an algorithm for selecting a signal according to a signalquality measurement, and a processor configured to combine the signalsreceived from the first antenna and the second antenna in a proportionbased on the algorithm. The signal quality measurement may include aSignal to Interference plus Noise Ratio (SINR), Signal to InterferenceRatio (SIR), or Signal to Noise Ratio (SNR).

Aeronautical broadband communication may also be enhanced by providing afirst and third antenna configured to communicate using a signalorientation corresponding to a first polarization, and a second andfourth antenna configured to communicate using a signal orientationcorresponding to a second polarization, with one or more processorswhich combine the signals from the first and third antennas, and furthercombine the signals from the second and fourth antennas, using analgorithm for selecting a signal according to a signal qualitymeasurement, thereby improving signal quality for each polarization. Aprocessor may handoff communication responsibilities from the first andthird antennas to the second and fourth antennas.

Polarization Reuse

Referring to FIG. 1 a, an airborne RF communication transceiver isdisposed at an aircraft as part of an aeronautical broadband system. Inthis system, a cellular network of base stations is deployed withantennas that are designed to provide coverage for aircrafts at highaltitudes. In an aeronautical application, a clear line of sight isalmost always available from an aircraft from a base station, retainingthe polarization of any signal transmitted between them. These basestations may relay a composite signal to a modem disposed at theaircraft, which in turn can communicate with WCDs disposed throughoutthe aircraft. Alternately, or in the event of an emergency, the basestations may relay a polarized signal directly to an individual WCD suchas a personal telephone.

Although shown on a traditional aircraft, the apparatuses, systems, andmethods disclosed herein are equally applicable to all air vehicles,space vehicles, oceanic vehicles, and land vehicles. It will beimmediately recognized that the apparatus, systems, and methodsdisclosed herein are useful whenever conditions allow for a polarizedbeam to substantially retain its polarization over a transmissiondistance.

Still referring to FIG. 1 a, a first antenna 100 is disposed at anaircraft and configured to communicate using signal 104 having anorientation corresponding to a first polarization.

As is known in the art, an antenna may be placed at various locations onan aircraft. Different locations provide certain advantages, and thechoice in location may be limited by the length of the antenna,proximity to power sources, proximity to sources of interference, andother factors known in the art. Antenna 100 location and orientationcontributes to the polarization of signal 104. In addition, reflectionoff the exterior surface of the aircraft can change the polarization ofwaves transmitted or received at the antenna and hence change the signalorientation. As a result, choice of a first polarization will alsoinfluence the choice of a location for the antenna. It is noted that thelocation of antenna 100 on the aircraft as shown in FIG. 1 a is anexample; therefore, an antenna may be located in any place on theaircraft that meets the desirable conditions discussed above.

Also disposed at the aircraft is a second antenna 108 configured tocommunicate using signal 112 having an orientation corresponding to asecond polarization. Second antenna 108 is therefore configured in asimilar manner to antenna 100.

Antennas 100, 108 may, individually or collectively, be connected toamplifiers, passive or active signal boosters, or radio equipment suchas receivers. As an example, antennas 100, 108 may be connected to aprocessor 110 for establishing communication links using the antennas.Processor 110 may be a monolithic processor or a chipset, containinginstructions for establishing a communication link with a terrestrial oraeronautical transceiver. The processor 110 may contain programming forcommanding the antennas 100, 108 to (for example) activate, deactivate,or change polarization. The processor may also contain commands forencoding and decoding data, multiplexing and demultiplexing signals,storing and routing packets of information, and/or establishing andmaintaining communication links with another entity.

The polarization of first signal 104 has at least one characteristicdifference from the polarization of second signal 112. As an example,the first polarization may be substantially orthogonal to the secondpolarization. The first polarization may be substantially horizontalwhile the second polarization may be substantially vertical.

Alternately, the first polarization may be substantially right-circularand the second polarization may be substantially left-circular.

If the first and second polarizations are orthogonal to each other,first antenna 100, being configured to communicate using signal 104,would ideally intercept none of signal 112 with which second antenna 108communicates. Similarly, second antenna 108 would ideally intercept noneof signal 104. However, it is acknowledged that the polarization ofsignal 104 might change upon reflection at a surface (such as a buildingface, a ground interferer such as a mountain or lake, or even anexternal surface of the aircraft). Accordingly, one may use a processor,such as that used for the beam-forming techniques discussed below, toisolate transmissions of a particular polarization.

Again, the location of antenna 108 on the aircraft as shown in FIG. 1 ais exemplary; an antenna may be located in any place on the aircraftthat meets the desirable conditions discussed above, and may be locatedadjacent to the first antenna. The location of second antenna 108 on theaircraft may depend on the location chosen for first antenna 100.

The effective doubling in bandwidth provided by the use of two antennasof differing polarization can be used to enhance reception, reduce deadspots, and increase the signal carrying capacity of the network. As anexample, a first radiator 124 may be disposed in a first cell site 134,and configured to communicate using signals 104 of the firstpolarization. A second radiator 128 may be disposed in an adjacent cellsite 136, and configured to communicate using signals 112 of the secondpolarization. In this way, transmissions from first call site 134 andsecond cell site 136 are far less likely to interfere with each other,effectively doubling the capacity of the communication system utilizingthe antennas 100, 108, and their associated radiators 124, 128. It canbe appreciated that such a design still need have only one radiator ineach cell site, and thus is no more expensive than a traditional(polarization-independent) cellular configuration.

As a further example, a third radiator 126 and fourth radiator 130 maybe disposed in one cell site 132. Each cell site in FIG. 1 a may besectorized, and the polarization used in adjacent sectors different, soas to reduce interference at the boundary between two sectors to enhancedata rates and increase capacity. As an example, each adjacent cell sitecould also have two radiators, configured to communicate using signals104, 112 of two substantially orthogonal polarizations. While thisconfiguration could nearly double the amount of equipment utilized ateach cell site, the effective increase in network capacity could providethe same advantages listed above, namely, to enhance reception, decreasedead spots, or increase the signal carrying capacity of the network.Signals 104, 112 could carry the same signal (allowing for advancederror correction and signal strength), or could carry different signals(increasing capacity).

As a further example, not all cell sites need to have two radiators. Asshown in FIG. 1 a as examples, a cell site 140 may have three radiators(one in each sector), or a cell site 144 may have six radiators (two ineach sector). One could place a second radiator in sites where it isadvantageous: as examples, where interference is expected to be great,where higher capacity is needed, or where conditions are otherwisereliably poor for broadband communication.

Processor 110 may receive signals from each of antennas 100, 108;calculate a signal quality measurement from each of antennas 100, 108;and handoff communication responsibilities from one of the antennas tothe other of the antennas when the signal quality measurement of one ofthe antennas is lower than the signal quality measurement of the otherof the antennas. Such a handoff takes place when a wirelesscommunication device or base station determines that signal quality is,or is expected to be, better on one polarization than on the other. Theinitiator, either the device or the base station, sends instructions tothe other that a switch is to take place, and receives a signal that theinstructions have been received and are confirmed. At this time, the twodevices begin broadcasting on the new polarization, and confirm eachother's presence on the new polarization. Alternately, a single devicesuch as the processor 110 may perform a handoff from one base station(having a first polarization) to a second base station (having a secondpolarization). The processor 110 sends a command to the first antenna100 to instruct the base station of the same polarization 124 that ahandoff will occur.

The base station 124 is optionally networked to base station 128, andmay alert base station 128 to expect signals from the processor 110. Theprocessor 110 via antenna 108 then initiates communication on the secondpolarization. During the handoff the processor 110 may transmit on bothpolarizations until the base station 128 has detected the signal 112sent with the second polarization type, at which time the processor 110stops transmitting to the base station 124 with signal 104 sent with thefirst polarization type. This is only one type of handoff—many othershandoff methods are known to those skilled in the art and are applicableto the present inventive subject matter.

The signal quality measurement by which a decision to hand off is mademay be (as examples) a signal to interference ratio (SIR), a signal tonoise ratio (SNR), a signal to interference and noise ratio (SINR), orany other signal quality calculation. Such a processor 110 wouldnormally be disposed at the aircraft, and may be a part of the aircraftmodem as described above. It is also possible to use a processordisposed at an end-user's telephone, which could perform the sameresponsibilities if needed. This handoff process could assure that thepolarization providing the strongest signal is being utilized when bothradiators are disposed in the same cellular site, or could beresponsible for switching from one cell site having a first polarizationto a second cell site having a different polarization. As a furtherexample, a processor could be disposed on the ground and communicatewith radiators 124, 128 rather than with antennas 100, 108. Theprocessor could use the relative signal strength and/or signal qualitycalculation to determine the ideal communication polarization, andinstruct an additional processor at the aircraft to use one or the otherpolarization.

Referring to FIG. 1 b, in some further embodiments, the aircraft may beprovided with two additional antennas. Antenna 101 is configured tocommunicate using signals 104 of the same first polarization used byantenna 100 and radiator 124, but is disposed at a different locationfrom antenna 100. Antenna 109 is configured to use signals 112 of thesame second polarization used by antenna 108 and radiator 128, but isdisposed at a different location from antenna 108. The locations shownare merely examples, and antennas of different polarization need notnecessarily be disposed near each other. One or more processors (such asprocessor 110) may combine the signals from antennas 100 and 101, usingan algorithm for selecting a signal according to a signal qualitymeasurement. In this way, the two antennas 100 and 101 are used for beamformation, and become a virtual directional antenna capable of beingaimed toward a desired target (such as cell site 134), or away from adesired interferer. This beam formation process will be discussed inmore detail below. The same processor 110 or a different processor maycombine the signals from antennas 108 and 109 in a similar manner,making a second virtual directional antenna of a different polarizationthan the first virtual antenna. In these embodiments, communicationresponsibilities are handed off from antennas 100 and 101 to antennas108 and 109 when one polarization is determined to be better thananother.

Of course, while a total of four antennas are shown disposed on theplane of FIG. 1 b, communication may be enhanced by the placement ofeven more antennas. Half of the antennas may have a first polarization(the “first group”), while the remaining half may have a secondpolarization (the “second group”). The antennas in the first group areconnected to a processor which can weight the signals received from eachof the first group's antennas according to a signal quality measurement.The antennas in the second group are connected to a processor which canweight the signals received from the second group's antennas, alsoaccording to a signal quality measurement. In this way, two virtualdirectional antennas are formed, with different polarizations. These twovirtual antennas are therefore highly tunable due to the greater signallocalizability provided by more antennas, and can then be aimed throughthe beam formation techniques discussed below toward two or more basestations of appropriate polarizations.

Again, a third radiator 126 and fourth radiator 130 may be disposed inone cell site 132. Each cell site in FIG. 1 b may be sectorized, and thepolarization used in adjacent sectors different, so as to reduceinterference at the boundary between two sectors to enhance data ratesand increase capacity. As an example, each adjacent cell site could alsohave two radiators, configured to communicate using signals 104, 112 oftwo substantially orthogonal polarizations. While this configurationcould nearly double the amount of equipment utilized at each cell site,the effective increase in network capacity could provide the sameadvantages listed above, namely, to enhance reception, decrease deadspots, or increase the signal carrying capacity of the network. Signals104, 112 could carry the same signal (allowing for advanced errorcorrection and signal strength), or could carry different signals(increasing capacity).

Again, not all cell sites need to have two radiators. As shown in FIG. 1b as examples, a cell site 140 may have three radiators (one in eachsector), or a cell site 144 may have six radiators (two in each sector).One could place a second radiator in sites where it is advantageous: asexamples, where interference is expected to be great, where highercapacity is needed, or where conditions are otherwise reliably poor forbroadband communication.

Referring to FIG. 2, in some further embodiments, the aircraft may beprovided with a single antenna 200 capable of reconfiguration such that,in a first configuration, it communicates using signals 216 having anorientation corresponding to a first polarization, and in a secondconfiguration, it communicates using signals 220 having an orientationcorresponding to a second polarization. The reconfiguration may beachieved through rotation, beam forming, or other mechanical ornonmechanical adjustment. These polarizations may be substantiallyorthogonal to each other. Shown is a cellular network as described abovein which each cell site 204 contains two radiators 208, 212 configuredto communicate using signals 216, 220 having orientations correspondingto substantially orthogonal polarizations, or of two polarizations thatdiffer as set forth above. Again, a processor 224 disposed at theaircraft can use the relative signal strength or a signal qualitymeasurement to determine the ideal communication polarization, and thenmake use of the best polarization by configuring the antenna.Alternately, a processor connected to the two radiators could tune thepolarization of the aircraft antenna by remote instructions.

Of course, as a further example as set forth above, alternating cellsites could have radiators of alternating polarization. In thisconfiguration the aircraft reconfigures its antenna to utilize one orthe other polarization as it passes from one cell site to the next. Asyet another example, each cell-site radiator could also adjust itspolarization to improve signal quality, instructing one or more aircraftto adjust their polarizations accordingly.

Charted in FIG. 3 is a method for enhancing aeronautical broadbandcommunication. The method includes: establishing (step 300) a firstcommunication link with a first radiator using a signal orientationcorresponding to a first polarization, and establishing (step 304) asecond communication link with a second radiator using a signalorientation corresponding to a second polarization having at least onecharacteristic difference from the first polarization. The radiators maybe configured in one or more of the manners set forth above, or in manyother manners which will be clear to one skilled in the art upon readingthis disclosure. Communication may be established, as an example, by anaircraft having one or more antennas as set forth above. The method canalso include taking (step 308) signal quality measurements with respectto the radiators, comparing quality measurements (step 310) to determineif the difference between the measurements is above a given sufficiencythreshold, and handing off (step 312) communication responsibilitiesfrom one of the radiators to the other of the radiators when the signalquality measurement of one radiator is sufficiently higher than that ofanother. Of course this handoff can occur whenever one measure issignificantly lower than another (where difference below an acceptablethreshold is ignored), or whenever one measure is at all lower thananother.

A system may also be provided for enhancing aeronautical broadbandcommunication, as shown in FIG. 4. The system has means 400 forestablishing a communication link with a first radiator using a signalorientation corresponding to a first polarization, such as (by way ofexample) an antenna disposed at an aircraft and configured tocommunicate using waves of a first polarization establishing acorresponding signal orientation, and a processor connecter thereto. Thesystem also has means 404 for establishing a communication link with asecond radiator using a signal orientation corresponding to a secondpolarization substantially orthogonal to the first polarization, such as(by way of example) a second antenna of a different configuration thanthat of the first antenna at the same aircraft and connected to the sameprocessor. The system can also include means 408 for taking signalquality measurements with respect to each of the radiators, such as (byway of example) a processor containing instructions to perform an SNIR,and means 412 for handing off communication from one radiator to anotherbased on the signal quality measurement, such as (by way of example) arelay which connects a signal source 416 from one antenna or anotherwhen the SNIR is greater at one antenna than at another.

A machine readable medium may be provided having instructions forestablishing a communication link with a first radiator using a signalorientation corresponding to a first polarization and instructions forestablishing a communication link with a second radiator using a signalorientation corresponding to a second polarization substantiallyorthogonal to the first polarization. A machine-readable medium includesany mechanism that provides (i.e., stores and/or transmits informationin a form readable by a machine (e.g., a computer). For example, amachine-readable medium includes, but is not limited to, read onlymemory (ROM); random access memory (RAM); magnetic disk storage media;optical storage media; flash memory devices; electrical, optical,acoustical or other form of propagated signals (e.g., carrier waves,infrared signals, digital signals, etc.); storage media; radio channels;and wireless channels and various other mediums capable of storing,containing, or carrying instructions and/or data.

A processor may be provided having circuitry for establishing acommunication link with a first radiator using a signal orientationcorresponding to a first polarization, and circuitry for establishing acommunication link with a second radiator using a signal orientationcorresponding to a second polarization substantially orthogonal to thefirst polarization. The processor may be a monolithic integrated circuitor a chipset.

Beam Forming

Referring now to FIG. 5, some further embodiments of the presentinventive subject matter enhance aeronautical broadband communicationwith a beam-forming apparatus having a first antenna 500 and a secondantenna 504 disposed at an aircraft or other vehicle, such as thosevehicles discussed above. In beam-forming, signals from a discrete setof antennas (which may be directional or non-directional) are combineddigitally or electrically to simulate a larger, directional antenna. Theantennas may be individually or simultaneously connected to amplifiers,passive or active signal boosters, or radio equipment such as receivers.A processor 512 is configured to combine the signals received from thefirst antenna and the second antenna in a proportion based on analgorithm for selecting a signal according to a signal qualitymeasurement. The signal quality measurement may include a Signal toInterference plus Noise Ratio (SINR), Signal to Interference Ratio(SIR), Signal to Noise Ratio (SNR), or any of the many signal qualitymeasurements known in the art. The signal quality measurement mayinclude a first measurement from the first antenna and a secondmeasurement from the second antenna, where the algorithm includes aMinimum Mean Squared Error (MMSE) algorithm, an Equal Gain Combining(EGC) algorithm, a Maximal Ratio Combining (MRC) algorithm, or any otherconvenient combining algorithm applied to the first measurement and thesecond measurement. The beam may be formed adaptively, and the weightingof the antennas may be adapted on-the-fly.

As an example, if the first antenna 500 has a high signal qualitymeasurement, while the second antenna 504 has a low signal qualitymeasurement, the algorithm will select for the first antenna 500, andthe processor 512 will combine the signals from the antennas 500, 504 insuch a way that a greater weight is made to the first antenna 500 thanto the second antenna 504. In this manner, a “beam” is formed in adirection outward from the first antenna 500 (shown as field strengthdiagram 508). When the antennas are used for receiving transmissions,the two antennas thus function as a virtual single directional antenna,pointed in the direction of the first antenna and thus receiving signalsfrom this direction in particular. When the antennas are used forbroadcasting, the two antennas again function as a virtual singledirectional antenna, sending energy in the selected direction. Beamformation may also improve signal quality by nulling signals in otherdirections.

The algorithm for signal quality measurement may be based on datareceived at the aircraft or at one or more base stations on the ground.Accordingly, when the antennas are used for receiving signals, a beammay be formed in the direction of the signal of highest quality asmeasured at the antenna. If the antennas are also (or alternately) to beused for broadcasting, the receiving sites can report a signal qualitymeasurement to the processor, and the processor can use the algorithm toform a transmission beam in the direction of the receiving site whichreports the highest quality signal. Thus, the algorithm may select aradiator 516 at a geographic location such as a cell site 520 forcommunication characteristics, and the processor may combine the signalsreceived from the first antenna and the second antenna so as to form abeam toward the radiator 516.

Although the above example shows how a beam may be formed toward aradiator 516 having a high signal quality measurement (or away from aradiator having a low signal measurement or which is a high source ofinterference), the presently disclosed inventive subject matter can alsobe used to direct a beam toward a radiator 516 having a low signalquality measurement as well. In this way, the beam-formed “virtualantenna” can be tuned toward a weak signal to boost reception or toprovide a stronger transmission in that direction.

By adjusting the proportion of signal sent to or received from aplurality of antenna elements, one can form a beam toward a desired basestation and put a null toward an interfering base station. One mayfurther form a beam on the transmit side toward a desired base stationand reduce interference toward any other base stations therebyincreasing the reverse link capacity. The above examples refer to twoantennas, however, any number of antennas may be used to resolve a moreaccurate beam or to improve signal strength.

Multiple transmit chains with their own filtering and power amplifiesmay be used when one wishes to match (a) the coefficient used to weightthe signals from each transmit path, with (b) a coefficient which may bechosen to be the same as the one that is used to weigh the signals onthe received side. Referring to FIG. 6, the apparatus may have a firsttransmit chain 620 which produces signals at a ratio determined from thealgorithm, and a second transmit chain 624 which produces signals at aratio determined from the algorithm. The first transmit chain 620 mayhave at least one filter 628, at least one power amplifier 632, and atleast one radiator 644 and the second transmit chain may have at leastone filter 636, at least one power amplifier 640, and at least oneradiator 648. The chains 620, 624 may of course contain other elementsas well. All of the elements of the chains 620, 624 may be connected inany useful order. Thus to allow for beam-formed tuning of bothbroadcasting and receiving, the algorithm may select a radiator 616 forcommunication characteristics, a processor (not shown) may combine thesignals received from a first antenna and a second antenna (also notshown) so as to form a beam toward the radiator 616, and the processormay further produce signals at the first transmit chain 620 and thesecond transmit chain 624 so as to form a beam toward the radiator 616.

Referring to FIG. 7, some embodiments of the present inventive subjectmatter enhance aeronautical broadband communication with a method havingthe steps of: performing (step 700) a signal quality measurement basedon signals from a first antenna, performing (step 704) a second signalquality measurement based on signals from a second antenna, feeding(step 708) the first signal quality measurement and the second signalquality measurement into an algorithm, and combining (step 712) thesignals received from the first antenna and the second antenna at aratio determined from the algorithm.

Referring to FIG. 8, some embodiments of the present inventive subjectmatter enhance aeronautical broadband communication with a system havinga first means 800 for receiving signals (by way of an example, anantenna) and means 804 for performing a first signal quality measurementbased on signals from the first receiving means 800 (by way of anexample, a processor which applies a SNIR measurement on the signal), asecond means 808 for receiving signals (by way of an example, anotherantenna) and means 812 for performing a second signal qualitymeasurement based on signals from the second receiving means 808 (by wayof an example, means 812 may be a processor which applies a SNIRmeasurement on the signal), means 816 for determining a desirableproportion for combining the signals received from the first receivingmeans 800 and the second receiving means 808 based on the first signalquality measurement and the second signal quality measurement (by way ofan example, a processor containing instructions using an algorithm foroptimizing output signal quality), and means 820 for combining thesignals received from the first receiving means 800 and the secondreceiving means 808 in the proportion (by way of an example, a digitalsignal processor connected to the two receiving means).

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a machine readable mediumhaving instructions for performing a first signal quality measurementbased on signals from a first antenna, instructions for performing asecond signal quality measurement based on signals from a secondantenna, instructions for feeding the first signal quality measurementand the second signal quality measurement into an algorithm, andinstructions for combining signals received from the first antenna andthe second antenna at a ratio determined from the algorithm. Amachine-readable medium includes any mechanism that provides (i.e.,stores and/or transmits information in a form readable by a machine(e.g., a computer). For example, a machine-readable medium includes, butis not limited to, read only memory (ROM); random access memory (RAM);magnetic disk storage media; optical storage medial; flash memorydevices; electrical, optical, acoustical or other form of propagatedsignals (e.g., carrier waves, infrared signals, digital signals, etc.);storage media; radio channels; and wireless channels and various othermediums capable of storing, containing, or carrying instructions and/ordata.

Some embodiments of the present inventive subject matter enhanceaeronautical broadband communication with a processor having circuitryfor performing a first signal quality measurement based on signals froma first antenna, circuitry for performing a second signal qualitymeasurement based on signals from a second antenna, circuitry forfeeding the first signal quality measurement and the second signalquality measurement into an algorithm, and circuitry for combining thesignals received from the first antenna and the second antenna at aratio determined from the algorithm.

The previous description of some embodiments is provided to enable anyperson skilled in the art to make or use the present invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof the invention. For example, one or more elements can be rearrangedand/or combined, or additional elements may be added. Further, one ormore of the embodiments can be implemented by hardware, software,firmware, middleware, microcode, or any combination thereof. Thus, thepresent invention is not intended to be limited to the embodiments shownherein but is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

Having described the invention in detail and by reference to theembodiments thereof, it will be apparent that modifications andvariations are possible, including the addition of elements or therearrangement or combination or one or more elements, without departingfrom the scope of the invention which is defined in the appended claims.

1. An apparatus for enhancing aeronautical broadband communication, theapparatus comprising: a first antenna configured to communicate using asignal orientation corresponding to a first polarization; a secondantenna configured to communicate using a signal orientationcorresponding to said first polarization; and at least one processorconfigured to combine the signals received from said first antenna andsaid second antenna in a proportion based on an algorithm for selectinga signal according to a first signal quality measurement selected fromone of a signal to interference plus noise ratio (SINR), a signal tointerference ratio (SIR), or a signal to noise ratio (SNR).
 2. Theapparatus of claim 1, the apparatus further comprising: a third antennaconfigured to communicate using a signal orientation corresponding to asecond polarization, said second polarization having at least onecharacteristic difference from said first polarization; a fourth antennaconfigured to communicate using a signal orientation corresponding tosaid second polarization; and the at least one processor configured tocombine the signals received from said third antenna and said fourthantenna in a proportion based on an algorithm for selecting a signalaccording to a second signal quality measurement selected from one of asignal to interference plus noise ratio (SINR), a signal to interferenceratio (SIR), or a signal to noise ratio (SNR).
 3. The apparatus of claim2, comprising said first polarization provided substantially orthogonalto said second polarization.
 4. The apparatus of claim 2, comprisingsaid first polarization provided as horizontal polarization and saidsecond polarization provided as vertical polarization.
 5. The apparatusof claim 4, wherein said algorithm applied to at least one of said firstand second signal quality measurements comprises one of a minimum meansquared error (MMSE) algorithm, an equal gain combining (EGC) algorithm,a maximal ratio combining (MRC) algorithm.
 6. The apparatus of claim 1,the apparatus further comprising: a first radiator configured tocommunicate using a signal orientation corresponding to said firstpolarization; and a second radiator configured to communicate using asignal orientation corresponding to said second polarization.
 7. Theapparatus of claim 6, comprising said first radiator and said secondradiator provided in one cell site.
 8. The apparatus of claim 6,comprising said first radiator and said second radiator provided inadjacent respective cell sites.
 9. The apparatus of claim 1, theapparatus further comprising: a processor configured to receive signalsfrom each of said antennas; configured to calculate a signal qualitymeasurement from each of said antennas; and configured to handoffcommunication responsibilities from one of said antennas to the other ofsaid antennas when said signal quality measurement of one of saidantennas is lower than said signal quality measurement of the other ofsaid antennas.
 10. The apparatus of claim 9, wherein said signal qualitymeasurement comprises one of a signal to interference and noise ratio(SINR), a signal to interference ratio (SIR), or a signal to noise ratio(SNR).
 11. A method for enhancing aeronautical broadband communication,the method comprising: establishing a first communication link with afirst radiator using a signal orientation corresponding to a firstpolarization; establishing a second communication link with a secondradiator using a signal orientation corresponding to said firstpolarization; performing a first signal quality measurement based onsignals from a first antenna, said first antenna having a signalorientation corresponding to said first polarization; performing asecond signal quality measurement based on signals from a secondantenna, said third antenna having a signal orientation corresponding tosaid first polarization; feeding said first signal quality measurementand said second signal quality measurement into a first combiningalgorithm; and combining the signals received from said first antennaand said second antenna at a ratio determined from said first combiningalgorithm.
 12. The method of claim 11, the method further comprising:performing a third signal quality measurement based on signals from athird antenna, said third antenna having a signal orientationcorresponding to a second polarization having at least onecharacteristic difference from said first polarization; performing afourth signal quality measurement based on signals from a fourthantenna, said fourth antenna having a signal orientation correspondingto said second polarization; feeding said third signal qualitymeasurement and said fourth signal quality measurement into a secondcombining algorithm; and combining the signals received from said thirdantenna and said fourth antenna at a ratio determined from said secondcombining algorithm.
 13. The method of claim 12, comprising said firstpolarization provided substantially orthogonal to said secondpolarization.
 14. The method of claim 12, comprising said firstpolarization provided as horizontal polarization and said secondpolarization provided as vertical polarization.
 15. The method of claim11, comprising said first and said second radiators provided in a singlecell site.
 16. The method of claim 11, comprising said first and saidsecond radiators provided in adjacent respective cell sites.
 17. Themethod of claim 11, the method further comprising: taking signal qualitymeasurements with respect to each of said radiators; and handing offcommunication responsibilities from one of said radiators to the otherof said radiators when said signal quality measurement of one of saidradiators is lower than said signal quality measurement of the other ofsaid radiators.
 18. The method of claim 17, wherein said signal qualitymeasurement comprises one of a signal to interference and noise ratio(SINR), a signal to interference ratio (SIR), or a signal to noise ratio(SNR).
 19. A system for enhancing aeronautical broadband communication,the system comprising: means for establishing a communication link witha first radiator using a signal orientation corresponding to a firstpolarization; and means for performing a first signal qualitymeasurement based on signals from a first receiving means, said firstreceiving means having a signal orientation corresponding to a firstpolarization; means for performing a second signal quality measurementbased on signals from a second receiving means, said second receivingmeans having a signal orientation corresponding to said firstpolarization; means for combining the signals received from said firstreceiving means and said second receiving means at said first optimalratio; and means for computing a first optimal ratio of signals fromsaid first receiving means and said second receiving means.
 20. Thesystem of claim 19, the system further comprising: means forestablishing a communication link with a second radiator using a signalorientation corresponding to a second polarization substantiallyorthogonal to said first polarization means for performing a thirdsignal quality measurement based on signals from a third receivingmeans, said second receiving means having a signal orientationcorresponding to a second polarization; means for performing a fourthsignal quality measurement based on signals from a fourth receivingmeans, said fourth receiving means having a signal orientationcorresponding to said second polarization; means for computing a secondoptimal ratio of signals from said third receiving means and said fourthreceiving means; and means for combining the signals received from saidthird receiving means and said fourth receiving means at said secondoptimal ratio.
 21. The system of claim 19, the system furthercomprising: means for taking signal quality measurements with respect toeach of said radiators; and means for handing off communicationresponsibilities from one of said radiators to the other of saidradiators when said signal quality measurement of one of said radiatorsis lower than said signal quality measurement of the other of saidradiators.
 22. A tangible computer-readable medium containinginstructions for enhancing aeronautical broadband communication, themedium comprising: instructions for establishing a communication linkwith a first radiator using a signal orientation corresponding to afirst polarization; instructions for performing a first signal qualitymeasurement based on signals from a first receiving means, said firstreceiving means having a signal orientation corresponding to a firstpolarization; instructions for performing a second signal qualitymeasurement based on signals from a second receiving means, said secondreceiving means having a signal orientation corresponding to said firstpolarization; instructions for combining the signals received from saidfirst receiving means and said second receiving means at said firstoptimal ratio; and instructions for computing a first optimal ratio ofsignals from said first receiving means and said second receiving means.23. The medium of claim 22, the medium further comprising instructionsfor establishing a communication link with a second radiator using asignal orientation corresponding to a second polarization substantiallyorthogonal to said first polarization; instructions for performing athird signal quality measurement based on signals from a third receivingmeans, said second receiving means having a signal orientationcorresponding to a second polarization; instructions for performing afourth signal quality measurement based on signals from a fourthreceiving means, said fourth receiving means having a signal orientationcorresponding to said second polarization; instructions for computing asecond optimal ratio of signals from said third receiving means and saidfourth receiving means; and instructions for combining the signalsreceived from said third receiving means and said fourth receiving meansat said second optimal ratio.
 24. The medium of claim 23, the mediumfurther comprising: instructions for taking signal quality measurementswith respect to each of said radiators; and instructions for handing offcommunication responsibilities from one of said radiators to the otherof said radiators when one of said radiators has a lower signal qualitymeasurement than the other of said radiators.
 25. A processor able toenhance aeronautical broadband communication, the processor comprising:circuitry for establishing a communication link with a first radiatorusing a signal orientation corresponding to a first polarization;circuitry for performing a first signal quality measurement based onsignals from a first receiving means, said first receiving means havinga signal orientation corresponding to a first polarization; circuitryfor performing a second signal quality measurement based on signals froma second receiving means, said second receiving means having a signalorientation corresponding to said first polarization; circuitry forcombining the signals received from said first receiving means and saidsecond receiving means at said first optimal ratio; and circuitry forcomputing a first optimal ratio of signals from said first receivingmeans and said second receiving means.
 26. The processor of claim 25,processor further comprising: circuitry for establishing a communicationlink with a second radiator using a signal orientation corresponding toa second polarization substantially orthogonal to said firstpolarization; circuitry for performing a third signal qualitymeasurement based on signals from a third receiving means, said secondreceiving means having a signal orientation corresponding to a secondpolarization; circuitry for performing a fourth signal qualitymeasurement based on signals from a fourth receiving means, said fourthreceiving means having a signal orientation corresponding to said secondpolarization; circuitry for computing a second optimal ratio of signalsfrom said third receiving means and said fourth receiving means; andcircuitry for combining the signals received from said third receivingmeans and said fourth receiving means at said second optimal ratio. 27.The processor of claim 26, the processor further comprising: circuitryfor taking signal quality measurements with respect to each of saidradiators; and circuitry for handing off communication responsibilitiesfrom one of said radiators to the other of said radiators when one ofsaid radiators has a lower signal quality measurement than the other ofsaid radiators.
 28. The processor of claim 25, comprising said processorprovided as a monolithic integrated circuit.
 29. The processor of claim25, comprising said processor provided as a chipset.